A CZ-4B launched the ZY-1 satellite on Oct. 14, 1999. The third stage of the launcher exploded in space five months later and produced more than 300 pieces of trackable debris. 240 pieces remained in orbit as of the end of Jan. 2001. (Photo: Xinhua News Agency)

by Wei LongBeijing - March 7, 2001China plans to set up a monitoring and research program to minimize space debris from its own launchers and satellites, China Space News reports in the Feb. 28 edition.

The proposed plan to increase China's capabilities to observe, avoid and reduce space debris received approval from specialists with the State Commission of Science, Technology and Industry for National Defense (COSTIND) on Feb. 22.

This is the first time the government organizes and plans a comprehensive national action plan on space debris research and monitoring to fulfill its international obligation in this area.

The five-year action plan calls for:

establishing an initial observing capability through a dedicated fixed telescope and two mobile telescopes, with a target resolving capability of 30 cm in the geosynchronous orbit;

developing a database on space debris environment and dynamics;

developing and putting into service an international level risk assessment and emergency avoidance expert system;

obtaining experimental data on active and passive protection through modelled experiments and computer simulations on materials and their structures, and fundamental theoretical research;

mitigating space debris generation, particularly in resolving the issue of venting residual propellant in the launcher's upper stage. Another issue is passivation of satellites at the end of their missions which includes meeting the requirements to exit the operational orbits.

China hopes that by 2005 the action plan not only gives its space program an independent ability to monitor orbital debris and issue warnings to protect its space assets, but also offers technical exchange and support to the international space community.

The Chinese-language space publication reported earlier in the Dec. 20, 2000 issue that five research institutions were involved in preliminary discussion of the action plan. Various working groups were formed to handle different topics in space debris research, such as overall modelling facilities, fine debris environment modelling, hypervelocity impact testing and analysis, dynamical modelling simulation and experimentation technology, and database development.

Space debris may be artifically produced, for example, remnants of deactivated satellites and launcher components and from on-orbit vehicle fragmentation, or it may occur naturally such as meteoroids.

China recognizes that space debris poses certain level of risk to its own space vehicles. However, there is currently very limited capability to monitor space debris and lacks any concerted research effort. The COSTIND evaluation committee members describe Chinese spacecraft as "defenseless" when it encounters space debris.

As the Shenzhou manned spacecraft becomes an important component of the space program, Chinese space officials see a need to establish a formal program to study and monitor orbital junk.

Members of the COSTIND evaluation committee also admit that China's effort to mitigate space debris production has not been as effective as hoped.

According to information obtained from the Orbital Information Group (OIG) at NASA Goddard Space Flight Center, as of Jan. 31, 2001 there were 339 pieces of trackable debris in orbit that came from Chinese space vehicles. This is the third highest number after the U.S. and the Commonwealth of Independent States (CIS).

In the past decade, Chinese launchers were responsible for two significant debris generation events. The first event occured on Oct. 4, 1990. According to the NASA report "Orbital Debris: A Chronology" published in Jan. 1999 (NASA TP-1999-208856), the third stage of a CZ-4 (Long March-4) rocket, which successfully delivered the Fengyun-1B (FY-1B) metsat into a polar sunsynchronous orbit a month earlier, exploded and created more than 80 trackable debris pieces at an altitude of 895 km. This was the second flight of CZ-4.

Chinese space officials said that subsequent analyses suggested that the likely cause of the explosion was mixing of residual hypergolic propellants.

Two officials from the Chinese Academy of Launch Vehicle Technology System Engineering Division (CALT-SED) announced in an international space conference in June 1993 that the upper stage of CZ-4 was redesigned to include residual propellant venting systems.

The change apparently was not implemented properly as another CZ-4 upper stage disintegrated on Mar. 11, 2000.

In this second debris generation event the third stage of a CZ-4B rocket, which successfully launched the Ziyuan-1 remote sensing satellite (ZY-1, also called the China-Brazil Earth Resources Satellite or CBERS-1) on Oct. 14, 1999, exploded and produced more than 300 fragments large enough to be tracked by the U.S. Space Surveillance Network (SSN). Most of these fragments initially clustered near an altitude of 735 km.

According to a report in the April 2000 issue of the NASA newsletter "Orbital Debris Quarterly News", the second CZ-4 upper stage disintegration was "the most significant satellite breakup in nearly four years".

Fine debris particles from this breakup were even detected by the space dust instrument SPADUS aboard the U.S. Air Force unclassified Advanced Research and Global Observation Satellite (ARGOS) in the weeks following the incident.

Despite the tainted record, China is serious about the issue of reducing space debris. The NASA report "Orbital Debris" wrote that the Chinese Academy of Space Technology (CAST) and other organizations formed an Orbital Debris Study Group in 1989, with representatives from the Ministry of Aerospace Industry, the Chinese Academy of Science (CAS), COSTIND, and the Foreign Ministry.

China has since participated in and hosted international conferences related to orbital debris. For example the 29th annual Space Safety and Rescue symposium of the International Academy of Astronautics (IAA) was held in conjunction with the 47th International Astronautical Federation (IAF) meeting in Beijing in Oct. 1996.

In Oct. 1994 the Inter-Agency Space Debris Coordination Committee (IADC) Steering Group and the IAF invited China to join the IADC. The Chinese space agency China National Space Administration (CNSA) officially accepted the membership in July 1995.

In an interview that the Xinhua News Agency dispatched on March 23, 1998, Yuan Jie, a researcher with the Shanghai Academy of Spaceflight Technology (SAST) which manufactures CZ-4 launchers, said that the China Space Law Association was set up in December 1997 to manage international space laws and issues regarding orbital debris.

Yuan added that SAST was actively studying debris in the low Earth orbit (LEO) environment and began to develop a database.

"China's ultimate goal is to cooperate with major nations involved in advanced space technology in order to effectively solve the issues regarding orbital debris," said Yuan.

Latest Chinese Launch Leaves Debris In Local VillageBeijing - Sept. 25, 2000A piece of the Changzheng-4B rocket that successfully launched the Ziyuan-2 remote sensing satellite has left its mark in a village near the city of Chongqing in the central Sichuan Province, the Yangtse Evening Post reported September 4.

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